编写一个程序，开启3个线程，这3个线程的ID分别为A、B、C，每个线程将自己的ID在屏幕上打印10遍

编写一个程序，开启3个线程，这3个线程的ID分别为A、B、C，每个线程将自己的ID在屏幕上打印10遍，要求输出结果必须按ABC的顺序显示；如：ABCABC….依次递推。

#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#include <string.h>
//#define DEBUG 1
#define NUM 3

int n=0;
pthread_mutex_t mylock=PTHREAD_MUTEX_INITIALIZER;//互斥量
pthread_cond_t qready=PTHREAD_COND_INITIALIZER;//条件变量


void * thread_func(void *arg)
{
    int param=(int)arg;
    char c='A'+param;
    int ret,i=0;
    for (; i < 10; i++)
    {
        pthread_mutex_lock(&mylock);
        while (param != n)  //刚运行时，n = 0， param = 0,条件不成立，所以直接打印A
        {
#ifdef DEBUG
            printf("thread %d waiting\n", param);
#endif
            ret = pthread_cond_wait(&qready, &mylock);
            if (ret == 0)
            {
#ifdef DEBUG
                printf("thread %d wait success\n", param);
#endif
            } else
            {
#ifdef DEBUG
                printf("thread %d wait failed:%s\n", param, strerror(ret));
#endif
            }
        }
       // printf("%d ",param+1);
        printf("%c ",c);  //打印A后
        n=(n+1)%NUM;      //n变成了1，对线程2会产出影响！！！！
        pthread_mutex_unlock(&mylock);
        //会唤醒所有的线程，因为当这个线程完后会等pthread_cond_wait()执行两次后才能退出while (param != n)
        pthread_cond_broadcast(&qready);

    }
    return (void *)0;
}

#if 0
//假设为线程2

void * thread_func(void *arg)//传入值1
{
    int param=(int)arg;
    char c='A'+param;
    int ret,i=0;
    for (; i < 10; i++)
    {
        pthread_mutex_lock(&mylock);
        while (param != n)  //和线程1同时执行，所以刚开始时条件满足
        {
#ifdef DEBUG
            printf("thread %d waiting\n", param);
#endif
            //执行到此时，等待线程1发送信号，当线程1的A打印完后，n的值也变成了1，条件就不成立了
            ret = pthread_cond_wait(&qready, &mylock);
            if (ret == 0)
            {
#ifdef DEBUG
                printf("thread %d wait success\n", param);
#endif
            } else
            {
#ifdef DEBUG
                printf("thread %d wait failed:%s\n", param, strerror(ret));
#endif
            }
        }
       // printf("%d ",param+1);
        printf("%c ",c); //此时打印值B
        n=(n+1)%NUM;    //对打印C的线程3产生影响！！！
        pthread_mutex_unlock(&mylock);
        pthread_cond_broadcast(&qready);
    }
    return (void *)0;
}

#endif

int main(int argc, char** argv) {

    int i=0,err;
    pthread_t tid[NUM];
    void *tret;
    for(;i<NUM;i++)
    {
        err=pthread_create(&tid[i],NULL,thread_func,(void *)i);
        if(err!=0)
        {
            printf("thread_create error:%s\n",strerror(err));
            exit(-1);
        }
    }
    for (i = 0; i < NUM; i++)
    {
        err = pthread_join(tid[i], &tret);
        if (err != 0)
        {
            printf("can not join with thread %d:%s\n", i,strerror(err));
            exit(-1);
        }
    }
    printf("\n");
    return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#include <string.h>
//#define DEBUG 1
#define NUM 3

int n=0;
pthread_mutex_t mylock=PTHREAD_MUTEX_INITIALIZER;//互斥量
pthread_cond_t qready=PTHREAD_COND_INITIALIZER;//条件变量


void * thread_func(void *arg)
{
    int param=(int)arg;
    char c='A'+param;
    int ret,i=0;
    for (; i < 10; i++)
    {
        pthread_mutex_lock(&mylock);
        while (param != n)  //刚运行时，n = 0， param = 0,条件不成立，所以直接打印A
        {
#ifdef DEBUG
            printf("thread %d waiting\n", param);
#endif
            ret = pthread_cond_wait(&qready, &mylock);
            if (ret == 0) 
            {
#ifdef DEBUG
                printf("thread %d wait success\n", param);
#endif
            } else 
            {
#ifdef DEBUG
                printf("thread %d wait failed:%s\n", param, strerror(ret));
#endif
            }
        }
       // printf("%d ",param+1);
        printf("%c ",c);  //打印A后
        n=(n+1)%NUM;      //n变成了1，对线程2会产出影响！！！！
        pthread_mutex_unlock(&mylock);
		//会唤醒所有的线程，因为当这个线程完后会等pthread_cond_wait()执行两次后才能退出while (param != n)
        pthread_cond_broadcast(&qready);
		
    }    
    return (void *)0;
}

#if 0
//假设为线程2

void * thread_func(void *arg)//传入值1
{
    int param=(int)arg;
    char c='A'+param;
    int ret,i=0;
    for (; i < 10; i++)
    {
        pthread_mutex_lock(&mylock);
        while (param != n)  //和线程1同时执行，所以刚开始时条件满足
        {
#ifdef DEBUG
            printf("thread %d waiting\n", param);
#endif
			//执行到此时，等待线程1发送信号，当线程1的A打印完后，n的值也变成了1，条件就不成立了
            ret = pthread_cond_wait(&qready, &mylock);
            if (ret == 0) 
            {
#ifdef DEBUG
                printf("thread %d wait success\n", param);
#endif
            } else 
            {
#ifdef DEBUG
                printf("thread %d wait failed:%s\n", param, strerror(ret));
#endif
            }
        }
       // printf("%d ",param+1);
        printf("%c ",c); //此时打印值B
        n=(n+1)%NUM;    //对打印C的线程3产生影响！！！
        pthread_mutex_unlock(&mylock);
        pthread_cond_broadcast(&qready);
    }    
    return (void *)0;
}

#endif

int main(int argc, char** argv) {
    
    int i=0,err;
    pthread_t tid[NUM];
    void *tret;
    for(;i<NUM;i++)
    {
        err=pthread_create(&tid[i],NULL,thread_func,(void *)i);
        if(err!=0)
        {
            printf("thread_create error:%s\n",strerror(err));
            exit(-1);
        }
    }
    for (i = 0; i < NUM; i++)
    {
        err = pthread_join(tid[i], &tret);
        if (err != 0)
        {
            printf("can not join with thread %d:%s\n", i,strerror(err));
            exit(-1);
        }
    }
    printf("\n");
    return 0;
}

结果如下：